Media content transceiving method and transceiving apparatus using same

ABSTRACT

The present invention relates to a method and apparatus for transceiving media content through the Internet. A media transmitting method according to one embodiment of the present invention transmits media content through the Internet, and comprises the steps of: configuring the media content with a plurality of representations; dividing each of the plurality of representations into a plurality of segments; dividing each of the plurality of segments into a plurality of sub-segments; generating a plurality of time reference values corresponding to each of the plurality of sub-segments; and transmitting any one of the representations, wherein the representation being transmitted comprises the plurality of time reference values. According to the one embodiment of the present invention, media content can be seamlessly played back due to switching a bit stream when the state of a network changes.

This application is a National Stage Entry of International ApplicationNo. PCT/KR2012/004867 filed Jun. 20, 2012, which claims benefit andpriority to U.S. Provisional Application No. 61/498,627 filed Jun. 20,2011 and 61/499,651 filed Jun. 21, 2011, which are hereby incorporatedin their entirety by reference.

TECHNICAL FIELD

The present invention relates to a method and device for transceivingmedia content through internet.

BACKGROUND ART

Digital broadcasting such as current terrestrial broadcasting, cablebroadcasting, or Digital Multimedia Broadcasting (DMB) mostly streams AVcontent by using MPEG-2 Transport Stream (TS).

Moreover, with recent fast growth of internet, multimedia serviceproviding content by using an Internet Protocol (IP) network as a maintransmission network is actively used and digital broadcasting such asstereo 3D video broadcasting, Ultra High Definition (UHD) broadcasting,multipoint 3D video broadcasting, and hologram broadcasting has evolvedin the direction requiring larger transmission capacity than before.

However, MPEG-2 TS including a 188 byte fixed length packet may beinefficient to transmit content having a higher resolution than anexisting HDTV by using an IP network.

DISCLOSURE OF THE INVENTION Technical Problem

Embodiments provide a transceiving method and device for streaming mediacontent efficiently according to a network state.

Technical Solution

In one embodiment, provided is a method of transmitting media contentthrough an internet. the method includes: configuring the media contentwith a plurality of representations; dividing the representation into aplurality of segments; generating time reference values respectivelycorresponding to subsegments in the segment, and transmitting one of therepresentations.

In another embodiment, provided is a method of receiving media contentthrough an internet. The method includes: receiving a firstrepresentation from among a plurality of representations including themedia content; stopping the receiving of the first representations andreceiving a second representation; and presenting the receivedrepresentation, wherein the received representation is divided into aplurality of segments and received and subsegments included in thesegment correspond to time reference values, respectively.

In further another embodiment, provided is a device of transmittingmedia content through an internet. The device includes: a media encoderconfiguring the media content with a plurality of representations; asegmenter dividing the representation into a plurality of segments; atime reference value generating unit generating time reference valuesrespectively corresponding to subsegments included in the segment; and atransmitting unit transmitting one of the representations.

In further another embodiment, provided is a device of receiving mediacontent through an internet. The device includes: a receiving unitreceiving one of a first representation and a second representationincluding the media content, and stopping receiving the firstrepresentation when receiving the second representation; and a controlunit presenting one of the first representation and the secondrepresentation, wherein the received representation is divided into aplurality of segments and received and subsegments included in thesegment correspond to time reference values, respectively.

Advantageous Effects

According to an embodiment of the present invention, when a bit streamswitches according to a change in a network state, media content may beplayed seamlessly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of a mediacontent transceiving system according to an embodiment of the presentinvention.

FIG. 2 is a view illustrating a structure of MPEG-2 TS.

FIG. 3 is a flowchart illustrating a media content transmitting methodaccording to an embodiment of the present invention.

FIG. 4 is a view illustrating a configuration of representationsincluding media content according to an embodiment of the presentinvention.

FIG. 5 is a view illustrating a configuration of a subsegment accordingto an embodiment of the present invention.

FIG. 6 is a view illustrating a presentation time of a subsegment.

FIG. 7 is a view illustrating the presentation times of subsegmentsusing a PCR.

FIGS. 8 and 9 are views illustrating a configuration of an MPEG-2 TS PCRInformation Box providing metadata on media content according to anembodiment of the present invention.

FIGS. 10 and 11 are views illustrating a configuration of a MediaAuxiliary Information Box providing metadata on media content accordingto an embodiment of the present invention.

FIG. 12 is a block diagram illustrating a media content receiving deviceaccording to an embodiment of the present invention.

FIG. 13 is a flowchart illustrating a media content receiving methodaccording to an embodiment of the present invention.

FIG. 14 is a block diagram illustrating a configuration of an IPTVreceiver according to an embodiment of the present invention.

FIG. 15 is a block diagram illustrating a configuration of an IPTVreceiver according to another embodiment of the present invention.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a media content transceiving method and a transceivingdevice using the same according to an embodiment of the presentinvention will be described in more detail with reference to FIGS. 1 to15.

In the following description, detailed descriptions of relatedwell-known functions or configurations will be omitted if they wouldobscure the invention with unnecessary detail. Also, the terms usedhereinafter are defined according to the functions of the presentinvention. Thus, the terms may vary depending on user's or operator'sintentions or practices. Therefore, the terms used herein must beunderstood based on the descriptions made herein.

A transmitting device and a receiving device according to an embodimentof the present invention may transmit/receive media content by using anIP based transmission system, and for example, media content may bestreamed by using the Transmission Control Protocol (TCP) and theHypertext Transfer Protocol (HTTP) through a web server.

The transmitting device may receive content from a content provider andmay convert the received content to transmit it, or may store and savethe received content in a media DataBase (DB).

For example, a media content provided from a content provider may followan MPEG-2 TS format or an ISO Base Media file format, and thetransmitting device may convert the media content into a format easy forIP-based delivery and then may transmit the converted media contentthrough a network such as an internet network or may store the convertedmedia in the media DB.

Moreover, the receiving device may receive a media content from thetransmitting device by using an IP-based system and then may convert thereceived media content to play it or store it in a local storage.

For example, the receiving device may convert the received media contentfrom the transmitting device into an MPEG-2 TS format or an ISO BaseMedia file format and then may process the converted media content toplay it or store it in a local storage medium.

Moreover, since an IP based open internet environment using the HTTPdoes not guarantee QoS, a bandwidth through which data are transmittedto a receiving device is changed dynamically depending on networktraffic, such that it may be difficult to obtain a stable and fixedbandwidth necessary for content file delivery.

For example, in a PC system that a user uses in a home, if software offrequent network transmission is installed or used, due to the increasein network traffic, a stable and fixed bandwidth may not be obtained andin order to resolve such an issue, a method of an internet gateway toallocate a bandwidth to specific software is devised but is not widelyused.

Additionally, even when a fixed bandwidth is secured in a receivingdevice, since an internet server, that is, a transmitting deviceoperating in an open internet environment, transmits service throughseveral different networks, it may be still difficult to secure QoS.

For example, services such as Youtube are provided through anothernetwork that a specific service provider operates such that, as theamount in network setting or traffic is increased during a transmissionprocess, content transmission may be delayed, content transmission maydrop, or content may be retransmitted.

The above-mentioned QoS guarantee issue may be a main factor that makescontent providers providing content service in an open internetenvironment feel difficult.

Moreover, in order to resolve the difficulty in the contenttransmission, an adaptive streaming method for appropriatelytransmitting/receiving content according to a network bandwidth by usinga play list file in an M3U format may be used.

The adaptive streaming method creates content files having differentbitrates with respect to one content and allows a request for a bitrateselection and transmission according to a bandwidth of a receivingdevice and since content is mostly transmitted using the HTTP protocolin an open internet environment, it is called HTTP Adaptive Streaming.

Hereinafter, a structure of a system for adaptive streaming will bedescribed with reference to FIG. 1 according to an embodiment of thepresent invention.

FIG. 1 is a block diagram illustrating a configuration of a mediacontent transceiving system according to an embodiment of the presentinvention.

Referring to FIG. 1, a system for adaptive streaming is configuredincluding a server 10, a distribution 20, and a client 30.

When the server 10 delivers Audio/Video (AV) as raw data to a mediaencoder 11, the media encoder 11 may convert the AV data into astreaming File Format of an MPEG-2 TS form.

Moreover, a stream segmenter 12 may divide an MPEG-2 TS file outputtedfrom the media encoder 11 into a plurality of segments.

For example, the streaming segmenter 12 may segment one file or areal-time MPEG-2 TS file into segments, each having a size for about 10sec playback, and then may store the segments in the distribution 20.

The client 30 may request the segmented files stored in the distribution20 by using the HTTP protocol and then may receive and play the files.

Additionally, the MPEG-2 TS file segments having different bitrates maybe stored in the distribution 20, and for this, there may be severalorigin web servers 21 storing MPEG-2 TS file segments encoded withdifferent specific bit rates in the distribution 20

For example, the MPEG-2 TS file segments encoded with a bitrate of 20kbps and the MPEG-2 TS file segments encoded with a bitrate of 500 kbpsmay have different file names and may be stored in the distribution 20.

Accordingly, when a bandwidth in a reception area is decreased, theclient 30 may request the file encoded with a bitrate of 20 kbps andthen play it for 10 sec and also may check the bandwidth periodicallyagain before 10 sec, that is, a playback time, elapse.

At this point, if the bandwidth is increased enough for transmitting ahigh quality file, the client 30 may request the transmission of a fileencoded with a bitrate of 500 kbps.

As a result, the client 30 may alternately receive contents encoded withbitrates of 20 kbps and 500 kbps adaptively according to a networkbandwidth and play them, and in the case of a poor bandwidth, thequality of an image may be deteriorated but an interrupted image may beminimized.

In order for the above-mentioned adaptive streaming using HTTP protocol,media content may be configured with a plurality of representations, andmedia content included in each of the representations may have differentbitrates, resolutions, languages or codecs.

Media content may include media components such as audio, video, ortimed text, and a representation may be a structured collection of oneor more media components.

In this case, the client 30 may request one of a plurality ofrepresentations configured to have different bitrates, as mentionedabove, from the server 20 and may receive it.

Moreover, in order for the client 30 to access segments and providestreaming service to a user, the server 10 may provide a MediaPresentation Description (MPD) including metadata required by the client30 in addition to segment data.

The client 30 may select one of a plurality of representations by usingan element in the MPD and then may request transmission.

The representation is segmented into the above-mentioned plurality ofsegments and may be transmitted as a segment or a partial segment inresponse to a request of the client 30 by using an HTTP GET or HTTPpartial GET method defined by HTTP 1.1 (RFC 2616).

On the other hand, if bitstream switching is available, the client 30may switch the received representation with another representation onthe basis of information updated during media playback.

In this case, the client 30 may receive and play a new representationfrom a time that a previous representation is played.

Additionally, a segment may be configured including a plurality ofsubsegments, and each subsegment may mean the smallest unit indexed in asegment level. The segment may include an Initialization Segment, aMedia Segment, an Index Segment, and a Bitstream Switching Segment.

FIG. 2 is a view illustrating a structure of MPEG-2 TS.

Referring to FIG. 2, each MPEG-2 TS may include a plurality of MPEG-2 TSpackets having a fixed bitrate of 180 bytes and each subsegment may beconfigured with a set of sequential MPEG-2 TS packets.

For example, one sample is an access unit configured with at least oneMPEG-2 TS packet having the same PID and a subsegment may be defined asone indexed set of access units sequential according to a decodingorder.

Moreover, a fragmented file structure may be used to stream an ISO BaseMedia file format.

For example, the fragmented file divides media tracks into a pluralityof fragments physically, and each fragment may be configured with aMovie Fragment (moof) box and a media data (mdat) box.

The mdat box following the moof box may include fragment media data anda pair of moof-mdat in such a combination may configure one fragment.

In this case, a subsegment may be defined as a self-contained set of atleast one sequential movie fragment, and accordingly, may include atleast one Movie Fragment (moof) box and at least one media data (mdat)box corresponding thereto.

According to an embodiment of the present invention, when a mediacontent in the above-mentioned MPEG-2 TS or ISO base media file formatis configured with a plurality of representations and transmitted by asegment unit, the server 10 may use a Program Clock Reference (PCR) toallow bit stream switching to be efficiently performed in the client 30.The PCR is information on a system clock in an MPEG-2 TS and mayindicate a time reference value with respect to a program.

Moreover, although the case that a media content in the MPEG-2 TS or ISObase media file format is transmitted to the internet through HTTP isdescribed exemplarily, the present invention is not limited thereto, anda media content transceiving method and device according to anembodiment of the present invention may be applicable to various formatsof media contents.

Hereinafter, embodiments for a media content transmitting methodincluding a PCR corresponding to a subsegment will be described withreference to FIGS. 3 to 7.

FIG. 3 is a flowchart illustrating a media content transmitting methodaccording to an embodiment of the present invention. Hereinafter, inrelation to a transmitting method below, a description of the samecontent described with reference to FIGS. 1 and 2 is omitted.

Referring to FIG. 3, the transmitting device configures media contentwith a plurality of representations in operation S101. For example, theplurality of representations may be configured differently depending onat least one of a bitrate, resolution, and language, and codec of amedia content.

The transmitting device divides each of the configured representationsinto a plurality of segments in operation S103. For example, each of therepresentations may be divided into a plurality of segments fortransmission using the HTTP protocol.

The transmitting device divides each of a plurality of configuredsegments into a plurality of subsegments in operation S105. For example,each of the media segments may be indexed by a subsegment unit accordingto a segment index.

FIG. 4 is a view illustrating a configuration of representationsincluding media content according to an embodiment of the presentinvention.

Referring to FIG. 4, the transmitting device may create a media contentincluding a Representation A and a Representation B having differentbitrates and the representations A and B may form one group. The groupmay further include other representations in addition to therepresentations A and B.

Moreover, there is index information on all subsegments included in therepresentations A and B and the index information may be used for theclient 30 to randomly access subsegments of a segment by using thepartial HTTP GET method.

For example, if each subsegment includes a segment index or there is anindex segment providing an index for subsegment.

A method of providing index information on subsegments will be describedin more detail with reference to FIGS. 8 to 11.

Additionally, in relation to a subsegment, the earliest presentationtime TE and the latest presentation time TL of the subsegment 200 may bedefined. Hereinafter, referring to FIG. 5, a configuration of asubsegment will be described according to an embodiment of the presentinvention.

FIG. 5 is a view illustrating a configuration of a subsegment accordingto an embodiment of the present invention.

Referring to FIG. 5, the subsegment 200 may include two mediacomponents, for example, video and audio, and one of the mediacomponents, for example, video, may be designated as a reference stream.

That is, the reference stream may mean a group of sequential samples ofa primary media component among the media components.

In this case, the earliest presentation time TE of the subsegment 200may be defined as the earliest presentation time of an arbitrary samplein the reference stream and accordingly, may be a presentation time ofthe earliest sample 201 among video samples.

Also, the latest presentation time TL of the subsegment 200 may be apresentation time of the latest sample 204 in the reference stream.

Moreover, the sample 204 may mean an access unit in a stream of thesubsegment 200 (or a segment).

Referring to FIG. 4 again, the subsegments shown in FIG. 4 may havedifferent sizes or different durations of media content.

Additionally, although the latest presentation time TL of a subsegmentpositioned at the boundary between sequential subsegments is shown inFIG. 4, the latest presentation time TL of a subsegment may be slightlyahead of the boundary between subsegments.

That is, in the representation A, the latest presentation time TL of thekth subsegment may be slightly ahead of a time corresponding to theboundary between the kth subsegment and the K+1th subsegment.

Hereinafter, referring to FIG. 6, a presentation time of subsegmentswill be described.

FIG. 6 is a view illustrating a presentation time of a subsegment.

Referring to FIG. 6, the earliest presentation time TE of the K−1thsubsegment (K−1)B of the representation B may be later than the latestpresentation time TL of the Kth subsegment KA of the representation A.

If the bit stream switches from the representation A to therepresentation B, the client 30 may present the representation B afterthe switching while presenting the representation A.

At this point, after receiving the Kth subsegment KA of therepresentation A and completely presenting it, the client 30 receivesthe K−1th subsegment (K−1)B of the representation B and presents it, anda time that a subsegment is not presented on the basis of a presentationtimeline occurs by the difference by the earliest presentation time TEof the K−1th subsegment (K−1)B of the representation B and the latestpresentation time TL of the Kth subsegment KA of the representation A.

Additionally, the earliest presentation time TE of the K+1th subsegment(K+1)B of the representation A may be ahead of the latest presentationtime TL of the Kth subsegment KB of the representation B.

If the bit stream switches from the representation B to therepresentation A, the client 30 may present the representation A afterthe switching while presenting the representation B.

At this point, since the client receives the subsegment (K+1)A of therepresentation B and presents it before receiving the Kth subsegment KBof the representation B and completely presenting it, a presentationtime of a subsegment may overlap on the basis of a presentationtimeline.

Accordingly, in order to prevent the case that a subsegment is notpresented during a bit stream switching process or presentation times ofsubsegments of different representations overlap, the earliestpresentation time TE of the Kth subsegment included in one of therepresentation A and the representation B needs to correspond to thelatest presentation time TL of the K−1th subsegment included in theother representation.

Referring to FIG. 3 again, the transmitting device creates a pluralityof PCRs corresponding to a plurality of subsegments in operation S107.The transmitting device may include the plurality of PCRs correspondingto the plurality of subsegments in an index segment. The transmittingdevice may allow bit stream switching to be smoother by transmitting aPCR.

Hereinafter, a method of using a PCR to allow the presentation times oftwo subsegments having different indices included in differentrespective representations to be mapped to a presentation timeline willbe described with reference to FIG. 7.

FIG. 7 is a view illustrating the presentation times of subsegmentsusing a PCR.

Referring to FIG. 7, the client 30 may switch the receivedrepresentation with another representation on the basis of informationupdated during media playback. For example, the client 30 may receivethe representation A including a media content encoded with a bitrate of500 kbps and the representation B including a media content encoded witha bitrate of 20 kbps alternately.

The client 30 may receive the K−1 the subsegment (K−1)B of therepresentation B because a bit stream switches while receiving the Kthsegment KA of the representation A.

The client 30 may extract a first PCR value of the Kth subsegment KA ofthe representation A and a second PCR value of the K−1th subsegment(K−1)B of the representation B while maintaining the presentation of theKth subsegment KA of the representation A. Then, the client 30 maycalculate a PCR difference value between the first PCR value and thesecond PCR value.

The client 30 may reflect the second PCR value and the PCR differencevalue to a first system clock S1 for the presentation of the K−1thsubsegment (K−1)B of the representation B. By reflecting a PCRdifference value of a subsegment in presentation and a subsegmentexpected to be presented to a system clock of the client 30, thepresentation times of subsegments may correspond to each other based ona presentation time line.

As mentioned above, if the presentation times of two subsegments havingdifferent indices included in different representations respectivelycorrespond to each other by using a PCR of a subsegment, even when theclient 30 performs bit stream switching on representations havingdifferent bitrates, duplicate data may not be provided and data may notbe damaged.

Referring to FIG. 3 again, the transmitting device transmits one ofrepresentations including a PCR corresponding to each of a plurality ofsubsegments in operation S109.

For example, the client 30 selects one of a plurality of representationshaving different bitrates, resolutions, languages, or codes of a mediacontent by using an MPD provided from the server 10 and may request asegment or a partial segment corresponding to the selectedrepresentation by using an HTTP GET or HTTP partial GET method definedby HTTP 1.1 (RFC 2616).

Moreover, the MPD may include a bitstream switching flag indicatingwhether to switch a bit stream on representations and a subsegmentalignment flag indicating whether to align subsegments.

If the bitstream switching flag in the MPD is ‘true’, the client 30 mayperform the above bitstream switching operation.

Additionally, if the subsegment alignment flag in the MPD is ‘true’,subsegments are aligned as shown in FIGS. 9 to 11, and accordingly, theclient 30 may switch a representation at the arbitrary boundary betweensequential subsegments without duplicate or missing data.

According to an embodiment of the present invention, there is indexinformation on all subsegments, and among a plurality orrepresentations, since the earliest presentation time TE of the Kthsubsegment included in an arbitrary first representation corresponds tothe latest presentation time TL of the K−1th subsegment included in anarbitrary second representation, data loss or duplicate receptionoccurring during bitstream switching may be prevented.

Moreover, in order to divide MPEG-2 TS media into segments fortransmission, a media may be roughly divided according to a duration ofa reference program element (this may have the same meaning as areference stream) as required by a transport protocol. A boundarybetween segments may be aligned with MPEG-2 TS packets.

In the metadata delivered for MPEG-2 TS media, one program elementbelonging to a program may be selected as a reference, and the earliestpresentation time for Play Unit (PU) with respect to a reference programelement in a segment may be delivered.

Additionally, with respect to each subsegment, a data offset and a stampPTS for the earliest presentation time of a corresponding subsegment maybe delivered, and the presentation time of a random access point and theinformation on whether PTS discontinuity occurs may be deliveredselectively.

Moreover, the presentation time of a random access point and theinformation on whether PTS discontinuity occurs may be used in order toallow the client 30 to adjust a PTS-PCR based timeline to a mediapresentation timeline.

The metadata may be expressed in a binary format based on typical ISOBase Media file format data types, and this may have a similar structureto a ‘sidx’ box used in Dynamic adaptive streaming over HTTP(DASH).

In addition to a function of the ‘sidx’ box, a format of metadataaccording to an embodiment of the present invention may allow the client30 to adjust an MPEG-2 PTS-PCR based timeline to a media presentationtimeline.

This is done by delivering the earliest PTS of a Play Unit PU in asubsegment, and additionally, information on discontinuity in the MPEG-2PTS timeline may be delivered.

Hereinafter, referring to FIGS. 8 and 9, PCR information included in anindex segment according to an embodiment of the present invention willbe described.

FIGS. 8 and 9 are views illustrating a configuration of an MPEG-2 TS PCRInformation Box providing metadata on media content according to anembodiment of the present invention.

Referring to FIG. 8, the metadata on media content may be configuredwith a MPEG-2 TS PCR Information Box ‘pcrb’, and the MPEG-2 TS PCRInformation Box ‘pcrb’ may provide PCR information for MPEG-2 TS.

The index segment may include indexing information of a media segment.The index segment may be an index segment for single media segment or anindex segment for multiple media segment.

The index segment for single media segment may accurately index onemedia segment. Each index segment indexing one media segment may startfrom a Segment Type box ‘styp’. In the segment type box ‘styp’, an indexsegment subsegment (isss), that is, a brand defined by an ISO basedmedia file format, may be shown. In an ‘isss’ brand, a single indexsegment may index an MPEG-2 TS based media segment.

Each index segment indexing one media segment may include one or moresegment index boxes and MPEG-2 TS PCR information boxes ‘pcrb’ in orderto accurately index one media segment. The MPEG-2 TS PCR informationboxes ‘pcrb’ may immediately follow a Segment Index box ‘sidx’documenting the same subsegment.

The index segment for multiple media segment may index a multiple mediasegment. Each index segment indexing multiple media segment may startfrom a Segment Type box ‘styp’. In the segment type box ‘styp’, an indexsegment media segment (isms), i.e., a brand defined by an ISO basedmedia file format, may be shown. In an ‘isms’ bland, a representationindex segment may index an MPEG-2 TS based media segment.

Each media segment may be indexed by one or more segment index boxes. Aplurality of segment index boxes for one given media segment may becontiguous.

Indexing information for a plurality of media segments may beconcatenated in the order expected by a single overall segment indexbox.

An overall segment index box may include one entry in a loop for eachmedia segment. Each entry may indicate segment index information for asingle media segment.

An index segment having a subsegment index may include an ‘ssss’ brandin the Segment Type box ‘styp’ as a compatible brand. In an ‘ssss’brand, a subsegment index segment may index an MPEG-2 TS based mediasegment.

An index segment having a subsegment index may follow an index segmentfor a single media segment defined to ‘0’ or may follow an index segmentfor a multiple media segment, but the present invention is not limitedthereto. A Sub-segment Index box ‘ssix’ may immediately follow after theSegment Index box ‘sidx’ or may immediately follow before the MPEG-2 TSPCR ‘pcrb’. The Segment Index box ‘sidx’ and the MPEG-2 TS PCRinformation box ‘pcrb’ may record the same subsegment. In such a way,the above segment index box ‘sidx’ may index only a plurality ofsubsegments.

Referring to the syntax structure of the MPEG-2 TS PCR information box‘pcrb’ shown in FIG. 9, subsegment_count may specify the number ofsubsegments of which some information is specified to the MPEG-2 TS PCRinformation box ‘pcrb’ and may be a positive integer. subsegment_countmay be identical to reference_count of a final segment index box.subsegment_count may be indexed in a loop and may be set to a valueequal to or greater than 1.

pcr indicates an MPEG-2 TS PCR corresponding to the first sync byte ofthe first MPEG-2 TS packet included in a media subsegment.

Hereinafter, referring to FIGS. 10 and 11, PCR information included inan index segment according to another embodiment of the presentinvention will be described.

FIGS. 10 and 11 are views illustrating a configuration of a MediaAuxiliary Information Box providing metadata on media content accordingto an embodiment of the present invention.

Referring to FIG. 10, the metadata on media content may be configuredwith a Media Auxiliary Information Box ‘masi’. The Media AuxiliaryInformation Box ‘masi’ may include auxiliary media information. TheMedia Auxiliary Information Box ‘masi’ may include information that asegment or a subsegment configuring a segment means a media type calledan MPEG-2 TS ‘m2ts’.

The index segment, as mentioned above, may be an index segment forsingle media segment or an index segment for multiple media segment butthe present invention is not limited thereto.

The index segment for single media segment may accurately index onemedia segment. Each index segment indexing one media segment may startfrom a Segment Type box ‘styp’. In the segment type box ‘styp’, thebrand ‘isss’ may be shown.

Each index segment indexing one media segment may include one or moresegment index boxes and Media Auxiliary Information Boxes ‘masi’ inorder to accurately index one media segment.

Referring to the syntax structure of the Media Auxiliary Information Box‘masi’ shown in FIG. 11, FormatID may be a unique identifier for data.FormatID may include four characters. Data may mean media data and thepresent invention is not limited thereto.

Referring to FIG. 10 again, the Media Auxiliary Information Box ‘masi’may immediately follow the Segment Index box ‘sidx’ documenting the samesubsegment. FormatID of the Media Auxiliary Information Box ‘masi’ maybe set to ‘m2ts’. The preceding 42 bits of the data field of the MediaAuxiliary Information Box ‘masi’ may include an MPEG-2 TS PCR. TheMPEG-2 TS PCR may correspond to the first MPEG-2 TS packet at an offsetthat the first offset first_offset indicates when a frequency is 27 MHz.A value of the next 6 bits of the data field of the Media AuxiliaryInformation Box ‘masi’ may be left as 0.

The index segment for multiple media segment may index a multiple mediasegment. Each index segment indexing multiple media segment may startfrom a Segment Type box ‘styp’. In the segment type box ‘styp’, ‘isms’,i.e., a brand defined by an ISO based media file format, may be shown.

Each media segment may be indexed by one or more segment index boxes. Aplurality of segment index boxes for one given media segment may becontiguous.

Indexing information for a plurality of media segments may beconcatenated in the order expected by a single overall segment indexbox.

An overall segment index box may include one entry in a loop for eachmedia segment. Each entry may indicate segment index information for asingle media segment.

An index segment having a subsegment index may include an ‘ssss’ brandin the Segment Type box ‘styp’ as a compatible brand.

An index segment having a subsegment index may follow an index segmentfor a single media segment defined to ‘0’ or may follow an index segmentfor a multiple media segment, but the present invention is not limitedthereto. The Sub-segment Index box ‘ssix’ may immediately follow afterthe Segment Index box ‘sidx’ or may immediately follow before the MediaAuxiliary Information Box ‘masi’. The Segment Index box ‘sidx’ and theMedia Auxiliary Information Box ‘masi’ may record the same subsegment.In such a way, the above segment index box ‘sidx’ may index only aplurality of subsegments.

Hereinafter, referring to FIGS. 12 and 13, a media content receivingmethod and device will be described according to an embodiment of thepresent invention.

The receiving device 300 according to an embodiment of the presentinvention may perform an operation of the client 300 as described withreference to FIGS. 1 to 11.

Additionally, since a configuration of a media content that thereceiving device 300 receives, for example, a configuration of arepresentation, a segment, and a subsegment, may be the same such asthat described with reference to FIGS. 3 to 7, its detailed descriptionwill be omitted below.

FIG. 12 is a block diagram illustrating a media content receiving deviceaccording to an embodiment of the present invention.

Referring to FIG. 12, the receiving device 300 includes a receiving unitand a control unit. The receiving unit includes an interface unit 310and the control unit includes a decoding unit 320 and a synchronizationunit 330.

A network interface unit 310, for example, an HTTP interface, mayreceive a media file together with synchronization information. Forexample, the network interface unit 310 may receive synchronizationinformation Sync Info. having the above-mentioned configuration byreferencing FIGS. 6 to 11 together with an MPEG-2 TS, and may receiveother media in a different format such as a 3GPP file format.

The decoding unit 320 may decode and output the media file that thenetwork interface unit 310 receives. The decoding unit 320 includes afirst decoder 321 for decoding other media received through the networkinterface unit 310 and a second decoder 322 for decoding an MPEG-2 TS,but the present invention is not limited thereto. The first decoder maybe a decoder for decoding media in different formats such as a 3GPP fileformat or may be an MPEG-2 TS decoder identical to the second decoder322. The second decoder 322 may be a typical MPEG-2 TS decoder. Thesecond decoder 322 may receive an MPEG-2 TS from the network interfaceunit 310 and decode it, and then may output the decoded Play Units andtheir PTSs.

The synchronization unit 330 may synchronize a media file the decodingunit 320 decodes with a media presentation timeline by using a mediapresentation time included in the synchronization information that thenetwork interface unit 310 receives.

Moreover, the synchronization unit 330 may identify a Play Unitincluding a media presentation time provided through the receivedsynchronization information. For this, the network interface unit 310may recover the PTSs of Play Units having a provided presentation timeand deliver them to the synchronization unit 330 or the PTS of acorresponding Play Unit needs to be provided from the transmittingdevice together with a presentation time. In order to recover a PTS,elementary stream time recovery may be used.

The synchronization unit 330 may synchronize MPEG-2 TS based mediaoutputted from the second decoder 322 with other media outputted fromthe first decoder 321 by using the decoding information (for example,media presentation times for Play Units) delivered from the transmittingdevice.

Moreover, the receiving device 300 may present the MPEG-2 TS based mediasynchronized by the synchronization unit 330 together with other media.

FIG. 13 is a flowchart illustrating a media content receiving methodaccording to an embodiment of the present invention. Hereinafter, inrelation to a receiving method below shown in FIG. 13, a description ofthe same content described with reference to FIGS. 1 and 12 is omitted.

Referring to FIG. 13, the receiving device 300 receives a firstrepresentation in operation S301 and presents the received firstrepresentation in operation S303.

For example, the receiving unit (not shown) equipped in the networkinterface unit 310 of the transmitting device 300 may request a segmentor a partial segment from the transmitting device through an HTTP GET orHTTP partial GET method defined by HTTP 1.1 (RFC 2616).

The network interface unit 310 may select one of a plurality ofrepresentations having different bitrates, resolutions, languages, orcodecs of a media content as a representation to be received by using anMPD received from the transmitting device

The network interface unit 310 determines whether bitstream switching isrequired during the presentation of a first representation in operationS305.

When bitstream switching is required for the second representation, thenetwork interface unit 310 receives the second representation inoperation S307.

The receiving device determines whether a bitstream switching flagbitstreamSwitchingFlag is ‘True’ by using an MPD provided from theserver 10 in operation S309.

If the bitstream switching flag bitstreamSwitchingFlag is ‘True’, thereceiving device may omit the step described below. Because, when thebitstream switching flag bitstreamSwitchingFlag is ‘True’, two segmentshaving different bitrates may be contiguous in an effective TS.

When the bitstream switching flag bitstreamSwitchingFlag is ‘False’, thereceiving device extracts a first PCR value from an index segment of afirst representation in presentation and then extracts a second PCRvalue from an index segment of a received second representation afterbitstream switching in operation S311. The index segment may include aPCR as described with FIGS. 8 to 11. The receiving device may extracteach PCR of a plurality of subsegments included in a representation fromthe index segment.

The receiving device calculates a PCR difference value between the firstPCR value and the second PCR value in operation S313. The PCR differencevalue is a value obtained by jumping a PCR between a plurality ofsegments of two representations having different bitrates and aplurality of subsegments.

Here, the first PCR value may be a PCR value corresponding to the lastMPEG-2 TS packet of a segment included in the first representation.Also, the second PCR value may be a PCR value corresponding to the firstMPEG-2 TS packet of a segment included in the second representation.

In such a way, the receiving device may perform a partial additionalMPEG-2 TS decoding operation to recover first and second PCR values froma media segment without the support of other devices.

The decoding unit 320 determines whether the second representationreceived in operation S307 is decoded in operation S315.

When a second representation is supplied to the decoding unit 320, thedecoding unit 320 executes a Free-run mode in operation S317. Once theFree-run mode is executed, the receiving device may prevent flushing ofbuffers of the first representation during presentation.

The receiving device determines whether the presentation of the firstrepresentation is completed in operation S319.

When the presentation of the first representation is completed, thereceiving device set a system clock by using the PCR difference valuecalculated in operation S313 and the second PCR value of the secondrepresentation in operation S321. The receiving device sets its systemclock to a value obtained by adding the PCR difference value and thesecond PCR value, so that bitstream switching occurs, the firstrepresentation and the second representation may be presentedseamlessly.

When the system clock is set to a new value, the decoding unit 320releases the Free-fun mode in operation S323.

The media content receiving and processing method described withreference to FIGS. 1 to 13 may be performed by an IPTV receiveraccording to an embodiment of the present invention.

Hereinafter, referring to FIGS. 14 and 15, a configuration of an IPTVreceiver according to an embodiment of the present invention will bedescribed in more detail.

FIG. 14 is a block diagram illustrating a configuration of an IPTVreceiver according to an embodiment of the present invention.

The IPTV receiver according to an embodiment of the present inventionmay include an additional tuner to receive terrestrial broadcasting,cable broadcasting, and satellite broadcasting. However, for convenienceof description, in the present invention, a configuration receiving anIPTV provided using an IP network will be mainly described.

Moreover, an ITF represents an Open IPTV Terminal Function and may meana receiver configured with a function module necessary for supportingIPTV service.

Referring to FIG. 14, the IPTV receiver includes a Network Interface501, a TCP/IP Manager 502, a Service Delivery Manager 504, a PVR Manager505, a Demux 508, a Data Decoder 507, an Audio/Video Decoder 512, an A/VDisplay & OSD Module 515, Application Managers 513 and 514, an SI &Metadata DB 511, a Service Discovery Manager 509, a Service ControlManager 503, a Metadata Manager 510, and a Content DB 506.

The network interface unit 501 receives packets received from a networkand transmits packets to the network. That is, the network interfaceunit 501 may receive service and media content from a service providerthrough a network.

The TCP/IP manager 501 is involved in packet delivery from a source to adestination with respect to a packet received by the IPTV receiver and apacket transmitted from the IPTV receiver. Additionally, the TCP/IPmanager 502 may classify the received packet to correspond to anappropriate protocol, and may output the classified packet to theService delivery Manger 504, the Service delivery Manager 509, theService control Manager 503, and the Metadata Manager 510.

The Service delivery Manager 504 is responsible for a control of thereceived service data. For example, in the case of controlling realtimestreaming data, an RTP/RTCP may be used.

When realtime streaming data are transmitted using an RTP, the Servicedelivery Manager 504 parses the received data packet according to an RTPto transmit it to the Demux 508 or store it in the Content DB 506according to a control of the service manager 514. Additionally, theService delivery Manager 504 may feed back network reception informationto a service side providing service by using an RTCP.

The Demux 508 demultiplexes the received packet into audio, video, andProgram Specific Information (PSI) data and then transmits them to theaudio/vide decoder 512 and the data decoder 507.

The data decoder 507 decodes service information such as ProgramSpecific Information (PSI), for example. That is, the data decoder 507may receive and decode a PSI section, a Program and Service InformationProtocol (PSIP) section, or a DVB-Service Information (SI) section,which are demultiplexed by the Demux 508.

Additionally, the data decoder 507 creates a database on serviceinformation by decoding the received sections, and stores the data onservice information in the SI & Metadata DB 511.

The audio/video decoder 512 decodes the video data and audio datareceived from the Demux 508. The audio/video decoder 512 may provide thedecoded audio data and video data to a user through the display unit515.

The application manager manages an overall state of the IPTV receiverand provides a user interface and also manages another manager. Forthis, the application manager includes a User Interface Manager 513 anda Service Manager 514.

The user interface manager 513 provides a Graphic User Interface (GUI)for user by using On Screen Display (OSD) and performs a receiveroperation according to an input by receiving a key input from a user.For example, when a key input on a channel selection is received from auser, a key input signal may be transmitted to the service manager 514.

The Service Manager 514 controls a service related manager such as theService delivery Manger 504, the Service Discovery Manager 509, theService control Manager 503, and the Metadata Manager 510.

Additionally, the Service Manager 514 creates a channel map and selectsa channel by using the channel map according to a key input receivedfrom the UI manager 513. Also, the Service Manager 514 receives serviceinformation of a channel from the data decoder 507 and sets audio/videoPacket Identifier (PID) of the selected channel to the Demux 508.

The Service discovery Manager 509 provides information necessary forselecting a service provider providing service. Upon receiving a channelselection from the Service Manager 514, the Service discovery Manager509 may find a service by using information necessary for selecting aservice provider.

The Service control Manager 503 is responsible for service selection andcontrol. For example, when a user select Live Broadcasting service suchas an existing broadcasting system, the Service control Manager 503 usesan IGMP or an RTSP, and when a user selects a service such as Video OnDemand (VOD), the Service control Manager 503 uses an RTSP, so that itcontrols service selection and control.

The RTSP protocol provides a trick mode on realtime streaming.Additionally, the Service control Manager 503 initializes and manages asession through an IMC gateway by using an IP Multimedia Subsystem (IMS)and a Session Initiation Protocol (SIP). The protocols are just oneembodiment and other protocols may be used according to animplementation.

The Metadata Manager 510 manages service related metadata and storesmetadata in the SI & Metadata DB 511.

The SI & Metadata DB 511 stores service information decoded by the datadecoder 507, metadata managed by the Metadata Manager 510, andinformation necessary for selecting a service provider provided by theService discovery Manager 509. Additionally, the SI & Metadata DB 511may store setup data for system.

The SI & Metadata DB 511 and the Content DB 506 may be realized by usingNonVolatile RAM (NVRAM) or flash memory and may be realized as logicallyseparated two areas on the same storage area.

The PVR Manager 505, as a module for recording and presenting livestreaming content, collects metadata on recorded content and generateenhanced information provided to a user, for example, a thumbnail imageor an index.

A function of a control unit of an IPTV receiver according to anembodiment of the present invention may be realized through a pluralityof divided modules, for example, the TCP/IP Manager 502, the ServiceDelivery Manager 504, the PVR Manager 505, the Application Managers 513and 514, the Service Discovery Manager 509, the Service Control Manager503, and the Metadata Manager 510.

For example, the TCP/IP Manager 502 may allow the Network Interface 501to request only a payload or segment corresponding to a specific package(for example, a package that the IPTV receiver subscribes) from a serverand receive it by filtering SD&S information through the above-mentionedtarget package information.

Moreover, the TCP/IP manager 502, by filtering SD&S information receivedin a multicast method through target package information, allows only apayload or segment corresponding to a specific package to be parsed andprocessed by the Data decoder 507.

FIG. 15 is a block diagram illustrating a configuration of an IPTVreceiver according to another embodiment of the present invention. Asolid arrow shown in FIG. 15 corresponds to a data path and a dottedarrow corresponds to a control signal path.

A Cable modem, DSL modem, etc 601, as an interface for allowing an ITFto connect to an IP Network in a physical level, restores a digitalsignal by demodulating a signal transmitted through a physical medium.

An Ethernet NIC 602 restores a signal received through a physicalinterface to IP data, and the IP Network Stack 607 processes each layeraccording to an IP Protocol stack.

Moreover, an XML Parser 609 parses XML Document among the received IPdata, and a File Handler 608 processes data transmitted in a file formatthrough FLUTE among the received IP data.

An SI Handler 611 processes a portion corresponding to IPTV serviceinformation among data received in a File format and stores theprocessed portion in the storage 612 and an EPG Handler 610 processes aportion corresponding to IPTV EPG information among data received in aFile format and stores the processed portion in the Storage 612.

The Storage 612 stores various data such as SI and EPG.

An SI Decoder 613 receives SI data from the Storage 612 and analysesthem to obtain channel map information, and an EPG Decoder 614 analyzesEPG data stored in the Storage 612 to restore information necessary forEPG configuration.

An ITF Operation Controller 615 is a main controller controlling anoperation of an ITF such as channel change or EPG display.

A Channel Service Manager 611 performs an operation such as channelchange according to a user input, and an Application Manager 617 mayperform application service such as EPG Display according to a userinput.

An MPEG-2 Demultiplexer 603 extracts MPEG-2 TS data from received IPDatagram and delivers it to a corresponding module according to packetidentification information PID.

Additionally, an MPEG-2 PSI/PSIP Parser 604 may extract PSI/PSIP dataincluding packet identification information PID of A/V data or accessinformation on a program element from an MPEG-2 TS and then may parsethem.

Moreover, an A/V Decoder 605 may decode inputted Audio and Video data todeliver them to a Display module 606, and the Display module 606 mayoutput the decoded A/V data or application.

Examples of the computer readable recording medium include read-onlymemory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes,floppy disks, and optical data storage devices, and carrier waves (suchas data transmission through the Internet).

The computer readable recording medium can also be distributed overnetwork coupled computer systems so that the computer readable code isstored and executed in a distributed fashion. Also, functional programs,codes, and code segments for accomplishing the present invention can beeasily construed by programmers skilled in the art to which the presentinvention pertains.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims.

The invention claimed is:
 1. A method for receiving a media content froma HTTP (hypertext transfer protocol) server, comprising: receiving themedia content including a representation which includes an index segmentand a plurality of media segments, wherein each media segment is dividedinto a plurality of subsegments and the index segment includes anoverall segment index box and a plurality of segment index boxes, andwherein each segment index box documents the plurality of subsegments ofeach media segment; extracting the overall segment index box in theindex segment, wherein the overall segment index box includes one entryin a loop for each media segment and each entry indicates segment indexinformation for a single media segment, wherein each segment index boxis followed by a PCR information box which documents the samesubsegments; extracting the PCR information box in the index segment,wherein the PCR information box includes a loop for the subsegments,wherein the loop in the PCR information box includes PCR information andzero-padding bits corresponding to each subsegment; and playing themedia content by using the PCR information.
 2. The method of claim 1,wherein the PCR information box comprises a PCR value corresponding to async byte of a foremost MPEG-2 TS packet contained in each of theplurality of subsegments.
 3. The method of claim 1, wherein the PCRinformation box comprises a subsegment count field which represents thenumber of subsegments indexed by the segment index box.
 4. The method ofclaim 1, further comprising: extracting a subsegment index box from theindex segment, wherein the segment index box is followed by thesubsegment index box.
 5. The method of claim 1, wherein the playing themedia content by using the PCR information comprises: mapping apresentation time of the media content to a media presentation timelineby using the PCR information.
 6. The method of claim 5, wherein themapping a presentation time of the media content to a media presentationtimeline by using the PCR information comprises: mapping a presentationtime of the media content to a media presentation timeline by using thePCR difference between a first subsegment and a second subsegment,wherein the first segment contains the first subsegment and the secondsubsegment.
 7. An apparatus for receiving a media content throughinternet, comprising: a receiving unit for receiving the media contentincluding a representation which includes an index segment and aplurality of media segments, wherein each media segment is divided intoa plurality of subsegments and the index segment includes an overallsegment index box and a plurality of segment index boxes, and whereineach segment index box documents the plurality of subsegments of eachmedia segment; a control unit for extracting the overall segment indexbox in the index segment, wherein the overall segment index box includesone entry in a loop for each media segment and each entry indicatessegment index information for a single media segment, wherein eachsegment index box is followed by a PCR information box which documentsthe same subsegments, extracting the PCR information box in the indexsegment, wherein the PCR information box includes a loop for thesubsegments, wherein the loop in the PCR information box includes PCRinformation and zero-padding bits corresponding to each subsegment, andplaying the media content by using the PCR information.
 8. The apparatusof claim 7, wherein the PCR information box comprises a PCR valuecorresponding to a sync byte of a foremost MPEG-2 TS packet contained ineach of the plurality of subsegments.
 9. The apparatus of claim 7,wherein the PCR information box comprises a subsegment count field whichrepresents the number of subsegments indexed by the segment index box.10. The apparatus of claim 7, wherein the control unit extracts asubsegment index box from the index segment, wherein the segment indexbox is followed by the subsegment index box.
 11. The apparatus of claim10, wherein the control unit maps a presentation time of the mediacontent to a media presentation timeline by using the PCR information.12. The apparatus of claim 11, wherein the playing the media content byusing the PCR information comprises: mapping a presentation time of themedia content to a media presentation timeline by using the PCRdifference between a first subsegment and a second subsegment, whereinthe first segment contains the first subsegment and the secondsubsegment.